This invention pertains to the art of bearings and more particularly to rolling type bearings.
The invention is particularly applicable to ball bearings of the semi-precision type in which at least one of the bearing races is formed from sheet metal and will be described with particular reference thereto; however, it will be appreciated by those skilled in the art that the invention has broader applications and may be advantageously employed in other environments and applications.
Semi-precision bearings of the type to which the present invention is directed have been heretofore known in the art. This type of bearing is typically employed in situations where extremely close tolerances for the bearings are not necessary or required as in, for example, toys, wheels, roller skates, some light non-precision machinery, conveyors, overhead doors and the like. One advantage for using such bearings is that they may be manufactured less expensively and in greater volume, thus reducing the overall cost of those articles on which they are employed.
Those bearings of the general type to which the subject invention is directed include coaxial inner and outer races with balls or rolling members disposed therebetween to permit ease of relative rotation between the races. The structures of the prior art semi-precision ball bearings have employed several materials for forming the races themselves including wire, bar stock and sheet metal. With regard to races formed from wire and bar stock, the forming processes have required several independent manufacturing steps. Each of these steps adds undesired costs to the final bearing structures because of the necessary labor and equipment expenditures. Moreover, the prior bearing races have comprised closed loop configurations in order to prevent any undesired separation or expansion of the races. These closed loops render it extremely difficult to assemble the overall ball bearing structure.
Prior bearing races constructed of sheet metal have taken many forms and also require that they be formed in a closed loop configuration. This configuration is necessary because of the physical property of spring back associated with the forming and working of sheet metal. Heretofore, final forming of the sheet metal races has only been through the elastic range so that there is a tendency for the races to spring back or expand somewhat from their final formed configuration. To eliminate these spring back or expansion problems, the ends of the sheet metal blanks which are formed into the races are rigidly affixed to each other as by welding or the like. The necessity for such joining adds additional costs to the overall bearing constructions and, again, makes assembly of the bearings more difficult.
The present invention contemplates a new and improved article and method which overcomes all of the above referred to problems and others and provides a ball or rolling bearing and method for making same which are simple, economical, dimensionally precise, permit easy fabrication of the bearing races, readily adapted for use with a plurality of bearing designs and readily adapted for use in a plurality of environments utilizing semi-precision bearings.